Torque Ripple Reduction in BLDC Motors with Considering Back EMF Harmonics and Optimization in Controlling Currents

Heretofore BLDC motors are widely used in many applications. One of the most important reasons limited BLDC motors applications is their high torque ripple, specifically commutation torque ripple. Till now, a lot of approaches have been proposed to solve this restriction. Recently, a new method based on supplying currents considering all harmonics of Back EMFs is proposed. this method is employed in this paper for three phase current conduction. Rotor frames provides AC direct and quadrant currents, hence applying the mention method is being problematic due to disturbances that AC current may make for PI controllers. Since in high speed remarkable torque ripples are detected, an adaptive notch filter to extract harmonic components and two different rotor frame to control currents are applied. While the latter is used for the fundamental component of currents, the former is used for harmonic components. It is notable that the second rotor frame is chosen based on the major harmonic component.

Keywords:

BLDC , torque ripple , back EMF , harmonic , component , controllers